Degradation of organic pollutants by methane grown microbial consortia |
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Authors: | Email author" target="_blank">Martin?HesselsoeEmail author Susanne?Boysen Niels?Iversen Lars?J?rgensen J?Colin?Murrell Ian?McDonald Stefan?Radajewski Helle?Thestrup Peter?Roslev |
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Institution: | (1) Department of Life Sciences, Section of Environmental Engineering, Aalborg University, Aalborg,, Denmark;(2) Norferm Denmark AS, Odense, Denmark;(3) Department of Biological Science, University of Warwick, Coventry,, UK |
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Abstract: | Microbial consortia were enriched from various environmental samples with methane as the sole carbon and energy source. Selected consortia that showed a capacity for co-oxidation of naphthalene were screened for their ability to degrade methyl-tert-butyl-ether (MTBE), phthalic acid esters (PAE), benzene, xylene and toluene (BTX). MTBE was not removed within 24 h by any of the consortia examined. One consortium enriched from activated sludge ( AAE-A2 ), degraded PAE, including (butyl-benzyl)phthalate (BBP), and di-(butyl)phthalate (DBP). PAE have not previously been described as substrates for methanotrophic consortia. The apparent Km and Vmax for DBP degradation by AAE-A2 at 20 °C was 3.1 ± 1.2 mg l–1 and 8.7 ± 1.1 mg DBP (g protein × h)–1, respectively. AAE-A2 also showed fast degradation of BTX (230 ± 30 nmol benzene (mg protein × h)–1 at 20 °C). Additionally, AAE-A2 degraded benzene continuously for 2 weeks. In contrast, a pure culture of the methanotroph Methylosinus trichosporium OB3b ceased benzene degradation after only 2 days. Experiments with methane mono-oxygenase inhibitors or competitive substrates suggested that BTX degradation was carried out by methane-oxidizing bacteria in the consortium, whereas the degradation of PAE was carried out by non-methanotrophic bacteria co-existing with methanotrophs. The composition of the consortium (AAE-A2) based on polar lipid fatty acid (PLFA) profiles showed dominance of type II methanotrophs (83–92% of biomass). Phylogeny based on a 16S-rRNA gene clone library revealed that the dominating methanotrophs belonged to Methylosinus/Methylocystis spp. and that members of at least 4 different non-methanotrophic genera were present (Pseudomonas, Flavobacterium, Janthinobacterium and Rubivivax). |
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Keywords: | activated sludge benzene BTX consortia degradation di-butyl-phthalate methanotrophic bacteria stable isotopes |
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